Introduction: Brick and Mortar Bowl
This is an entry in the
Epilog Challenge 9
Ever since I purchased my lathe I wanted to make bowls. I made a sled for segmented bowls a few months back and wanted to experiment with different patterns and wood. I love the look of paduke and walnut and decided on this brick and mortar pattern.
Most of the math and sled preparations are ignored in this instructable. If you want to see all that math and more, take a look at my Simple Sled for Perfect Segmented Bowls instructable.
Step 1: Tools and Materials
Step 2: Create Rings
Create your rings for your desired diameter. I wrote a very detailed instructable on how to use this sled for segmented bowls. The difference between that instructable and these rings is that these rings will have "mortar" segments made of walnut dividing each segment. I have uploaded a excel file that I use for planning bowls. Feel free to download and tinker with my formulas to suit your needs.
Step 3: Sand Segments
Once all of your segments and dividers are cut, sand each segment and verify that it fits as it should by holding them together with rubber bands.
Step 4: Glue Rings
Using either the rubber band or hose clamp method outlined here, glue rings together.
Step 5: Sand Rings Flat
Using a disc sander, sand the face of each ring flat. This will make the whole bowl glue up perfectly.
Step 6: Prep the Bottom of the Bowl
Using a solid piece of wood, turn it round and cut a recess in it to be accepted in the Nova Chuck. The recess shown here is not deep enough and will prove to be catastrophic later on. Be sure that your recess is as deep as the jaws of your chuck.
Step 7: Finish Bottom Segment
Attach the bottom ring to a waste block using turners tape. Turn the inside of the ring round. Turn the bottom solid wood portion down until it fits inside the ring. Glue the two together. Once dry, attach the bottom to the same waste block to finish the bottom. Turn the bottom around and mount in the Nova Chuck to ensure that it's round and flat.
Step 8: Segmented Bowl Glue-Up Jig
This simple jig is very helpful with these types of glue-ups. I actually found something similar made by Frank Howarth after I finished mine. There are a lot of great points that he has that could make mine better. This jig has a base of melamine to keep the glue from sticking with a length of all thread through the center to clamp even pressure across the segmented bowl.
I made a 12 x 12 inch square with two layers to provide added stiffness. Both layers of melamine and MDF were scraps I had around the garage which is why they are pieced together. Screw both layers together, locate and drill a hole the size of your threaded rod in the middle. My threaded rod measures 1/2 in. in diameter. Bolt from the top and bottom using washers to spread out the pressure. Add feet to the bottom for the clearance of the protruding threaded rod out of the bottom.
Not shown in this step is a larger handle I made for the nut. This allows for greater torque to be applied to the jig. However, a simple nut and wrench will work just as well.
Step 9: Glue Up
Starting at the top of the bowl (top down) glue two or three rings at a time. Since this pattern requires as much precision as possible, gluing only a few rings at a time help with lining everything up.
Alternate the rings to form the classic brick look. After each ring is glued in place, slide a board that's larger than the bowl and apply pressure with the bolt. Repeat this process until that remains is the final solid board.
Step 10: Glue Bottom in Place
Using adequate f clamps, glue the bottom of the bowl in place ensuring that everything is lined up as before.
Step 11: Turn
Mount the bowl in the lathe and turn the outside of the bowl. Support the bowl with a scrap piece of wood on the tailstock. Once the outside looks as you like, remove the tailstock and start on the inside.
This is where my bowl broke off the lathe. I'm sure that more experienced woodturners can tell me where I went wrong other than my recess not being deep enough. If you can give me some insight on how I can prevent this from happening in the future I would love to hear it!
Step 12: Repairing the Broken Bowl
Unfortunately at this point I was certain that I just formed a very expensive piece of firewood. Because of this I didn't take any pictures of the broken bowl. What I did to resolve the problem is I glued the top of the bowl to a scrap piece of wood. This allowed me to carefully turn the bottom of the bowl out and create a replacement with a deeper recess. The thin piece of MDF shown is to help with lining up the bottom when gluing it in place. Once dry, the MDF was turned off and the bowl was finished as it should have been before.
Step 13: Sanding
Once the outside and inside of the bowl are shaped to your liking, sand the entire bowl. I recently purchased this sander and it works amazingly well.
Step 14: Finish Bottom and Apply Finish
Remove the bowl from the lathe and sand the bottom to your liking. I mounted the bowl back in the lathe to apply a clear shellac finish to the outside and inside.
What scary lathe experiences do you have? I would love to hear them so I don't repeat them!
We have a be nice policy.
Please be positive and constructive.
Almost all of my jaw sets for my nova chucks have a dovetail profile for expansion gripping. They
will hold with a depth of as little as 1/8"; I usually go no deeper than 3/16", unless I see some
flaw in the wood that will cause it to split out under pressure. In any case, make sure there's
sufficient wood around the edge of the dovetail.
Or: for bowls like this, I've made the bottom thicker and screwed a faceplate to it. Drill out
the screwholes and insert decorative plugs. These can be either sawn off and sanded flush,
or left a little bit proud, giving the bowl some lift on its feet.
Be safe while sanding, Do not let your abrasives wrap around your hand or fingers. Ensure that
there's sufficient thickness by folding (some insist on folding in thirds, I find that it depends on
the abrasive and work) to keep built up heat from burning you. Always sand in the downward quadrant,
so that your fingers won't get jammed and the abrasive won't get thrown back at you. Watch out
for the corners of your fold; they can catch as badly as a mishandled gouge or chisel.
Using a disk sander in the manner shown to flatten the rings is a recipe for disaster (or at least very
short fingernails). Find some other way to do it that keeps your hands away from the abrasive.
If you don't like the idea of sticking your hand deep inside a spinning bowl (and you shouldn't) or the
bowl is of a hollow design, glue up a few rings at a time, finish the insides while the bowl is still
shallow enough for comfort.
Maybe you need something like this http://lumberjocks.com/projects/19235
I have been looking for a sanding device to finish the inside of a bowl, but do not want to spend a fortune. Foolishly, I just pressed a piece of sand paper inside and gently moved it back & forth. Bad move. Last week while sanding the inside of a bowl, I ripped most of my index finger nail off. Yes it hurt, but I was more upset about getting blood on the newly turned bowl. I will not do that again. I like the Sorby sanding tool you used in the Instructable. I guess it's time to spend a couple of dollars to save the rest of my fingers.
I don't have a chuck so I screw a turned waste block to a face plate & glue the face plate to the bottom of a bowl. I use a piece of newspaper between the waste block & the bottom of the bowl to make it easier to remove it from the waste block. I cut a small kerf in the waste block to allow a sharp chisel to fit & separate it when I'm finished. I'm a newbie, but this has worked several times.